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How Much House Can You Afford? The 28/36 Rule

The 28/36 rule is a long-standing guideline for estimating how much house fits inside a household's income. It caps housing costs at 28% of gross monthly income and total debt payments at 36%. This guide explains where those two numbers come from, how a down payment, interest rate, and existing debts move the answer, and why the amount a lender approves is often more than a household can comfortably carry.

By the MoneyHackWise Editorial Team · Reviewed for accuracy · 8 min read · Updated June 28, 2026

What the 28/36 rule actually measures

The 28/36 rule is built around two debt-to-income (DTI) ratios. DTI, as the Consumer Financial Protection Bureau defines it, is your monthly debt payments divided by your gross monthly income — that is, income before taxes and other deductions. The rule expresses two separate ceilings using that same income figure: 28% for housing alone, and 36% for all debt combined.

The 28% figure is the front-end ratio. It covers your total monthly housing payment, often abbreviated PITI: principal, interest, property taxes, and homeowners insurance. If the loan carries private mortgage insurance or homeowners-association dues, those belong here too. The idea is that no more than 28 cents of each pre-tax dollar should go toward keeping a roof over your head.

The 36% figure is the back-end ratio. It covers the housing payment plus every other recurring debt obligation: car loans, student loans, minimum credit card payments, personal loans, and similar. Everyday costs that are not debt — groceries, utilities, gas, childcare — are deliberately excluded from both ratios, which is one reason the rule is a starting point rather than a full budget.

Why there are two numbers, not one

Housing is usually the largest single line in a household budget, so the front-end ratio guards against a mortgage that is too large on its own. But two households with identical incomes can be in very different positions if one carries a car payment and student loans and the other carries none. The back-end ratio captures that difference by looking at the whole debt load together.

The two ceilings interact, and only one of them binds at a time. Subtract your existing non-housing debt payments from the 36% back-end cap, and whatever remains is the room left for housing under that ceiling. Your actual housing budget is the smaller of the 28% front-end cap and that leftover amount. When you carry little other debt, the 28% front-end number is usually the limiting factor; when you carry a lot, the 36% back-end number takes over and pulls your housing budget below 28%.

This is why paying down a car loan or a credit card before house-hunting can raise the price you can support even if your income never changes. Every dollar of monthly debt payment you eliminate is a dollar that moves back under the housing side of the 36% cap.

A worked example

Consider a household earning $96,000 a year, which is $8,000 in gross monthly income. The 28% front-end cap is 0.28 × $8,000 = $2,240 for the full housing payment. The 36% back-end cap is 0.36 × $8,000 = $2,880 for all debt combined. Suppose this household already pays $550 a month toward a car loan and a student loan. Subtracting that from the $2,880 back-end cap leaves $2,330 of room for housing. Because $2,240 (front-end) is smaller than $2,330 (back-end leftover), the front-end ratio binds, and the housing budget is $2,240.

Now translate that $2,240 into a home price. Assume property taxes and homeowners insurance run about $500 a month for the price range in question. That leaves $1,740 for principal and interest. At a 7% fixed rate on a 30-year loan, a $1,740 monthly principal-and-interest payment supports a loan of roughly $262,000 (using the standard mortgage payment formula, where the monthly payment equals the loan amount times r(1+r)ⁿ divided by (1+r)ⁿ−1, with r the monthly rate and n the number of months). With 20% down, that corresponds to a home price near $327,000; with 10% down, closer to $291,000, because a smaller down payment means a smaller loan for the same payment.

The example also shows how sensitive the answer is to the interest rate. Holding the $1,740 principal-and-interest budget fixed, a 6% rate supports about a $290,000 loan, 7% supports about $262,000, and 8% supports about $237,000. Nothing about the household changed — same income, same debts — yet a two-point swing in rates moved the supportable loan by more than $50,000.

How down payment, rate, and other debts each move the answer

A larger down payment lowers the loan amount for a given home price, which shrinks the monthly principal and interest and frees room under both ratios. Reaching 20% down on a conventional loan also lets a borrower avoid private mortgage insurance, which the CFPB notes is generally required on a conventional loan when the down payment is under 20% and which adds to the monthly payment. The trade-off is cash: a 20% down payment on a $327,000 home is about $65,000, versus roughly $16,000 at 5% down, so a bigger down payment raises affordability on paper but demands far more savings up front.

The interest rate works through the monthly payment. Because a mortgage is amortized, even a fraction of a percentage point changes the payment on a large balance, and the effect compounds over 30 years. When rates rise, the same monthly payment buys a smaller loan, so a household shopping at 8% simply cannot support the price it could have supported at 6% without either more income or more cash down.

Other debts work through the back-end ratio. Each existing monthly payment reduces the housing room left under the 36% cap dollar-for-dollar. A $550 monthly obligation, as in the example, removes $550 of potential housing budget the moment the back-end ratio becomes the binding constraint. This is the lever many buyers overlook: retiring a loan before applying can matter as much as saving a larger down payment.

Why "what you qualify for" is not "what you can comfortably afford"

Lenders often approve loans above 28/36. Qualified-mortgage rules require a lender to make a good-faith effort to assess a borrower's ability to repay, but as the CFPB explains, that assessment can rely on debt-to-income or on residual income, and different loan programs set different limits. Some approvals land well above a 36% back-end ratio. The 28/36 rule is a conservative guideline, not a legal cap, so the maximum a lender will extend is frequently larger than the number the rule produces.

The gap matters because both ratios use gross income, not take-home pay. After income taxes, payroll taxes, health insurance, and retirement contributions, a household nets meaningfully less than its gross, so a payment that looks like 28% of gross can be a much larger share of the money that actually hits the bank account. Neither ratio counts groceries, utilities, transportation, childcare, medical costs, or saving for goals — all of which still have to come out of that smaller net figure.

The practical consequence is that borrowing to the top of an approval can leave little margin for a job change, a medical bill, or a roof repair. The rule is useful precisely because it builds in headroom below what a lender might allow. Treating the approval amount as a target, rather than a ceiling, is the common mistake; the ratios are meant to be an upper bound to stay under, not a goal to reach.

Using the rule sensibly

The 28/36 rule is best used as a quick screen rather than a precise verdict. Start with gross monthly income, apply the two percentages, subtract existing debt payments from the back-end cap, and take the smaller of the front-end cap and the back-end leftover as the housing budget. That housing budget still has to be split among principal, interest, taxes, insurance, and any mortgage insurance or HOA dues before it becomes a home price, and only some of those pieces are within a buyer's control.

Because taxes, insurance, and rates vary widely by location and over time, running the numbers with local property-tax rates and current quotes gives a far more realistic result than a single national assumption. A mortgage payment calculator lets you test how a specific price, down payment, and rate combine into a monthly payment, and then that payment can be checked against the 28% and 36% caps.

Finally, the rule says nothing about the cash needed to close or the reserves left afterward. Down payment and closing costs are separate from the monthly-payment math, and depleting savings to hit a price can leave a household without an emergency cushion. A useful affordability picture combines the DTI ceilings with a clear-eyed look at both the monthly payment and the cash required to get to — and stay past — the closing table.

Frequently asked questions

Does the 28/36 rule use gross income or take-home pay?

Both ratios use gross monthly income — your income before taxes and deductions. That is how the Consumer Financial Protection Bureau defines debt-to-income ratio. Because take-home pay is lower than gross, a payment that equals 28% of gross can be a noticeably larger share of the money actually received, which is one reason the rule builds in a margin of safety.

What counts in the 36% back-end ratio but not the 28% front-end ratio?

The 28% front-end ratio counts only the housing payment — principal, interest, property taxes, homeowners insurance, and any mortgage insurance or HOA dues. The 36% back-end ratio counts all of that plus other recurring debts, such as car loans, student loans, and minimum credit card payments. Non-debt living costs like groceries and utilities are not counted in either ratio.

Can a borrower get approved for a mortgage above the 28/36 limits?

Often, yes. The 28/36 rule is a guideline, not a legal limit. Lenders must assess a borrower's ability to repay, but they can do so using debt-to-income or residual income, and different loan programs allow different thresholds — some well above a 36% back-end ratio. An approval amount can therefore exceed what the rule suggests, which is why the rule is meant as a conservative screen rather than a target.

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Sources & further reading

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Planning disclaimer

This guide is for general informational and planning purposes only. It does not provide personalized financial, investment, tax, legal, accounting, lending, or business advice.

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